1. Technical Field
The present invention relates to an apparatus for transmitting power and a control method thereof. More particularly, the present invention relates to an apparatus for transmitting high voltage power to a high voltage load, which prevents an arc strike by driving a high voltage relay after performing pre-charge control through a semiconductor switch and provides a fail-safe function by performing switching operation according to a fault of a vehicle and a state of a power relay assembly, and a control method thereof.
2. Description of the Related Art
Hybrid vehicle, fuel cell vehicles, plug-in hybrid vehicles, electric vehicles or the like employs energy of a high voltage battery to drive a motor. That is, electric energy of the high voltage battery is converted into mechanical energy through the motor to move the vehicle by rotating wheels of the vehicle.
A battery switch is provided between the high voltage battery and a vehicle component for driving the motor, such as an inverter, and performs switching operation such that voltage can be applied from the high voltage battery to the vehicle component such as the inverter via the battery switch.
When a fault occurs in the components or system of the vehicle, such a battery switch must be turned off as quick as possible in order to protect a system of the vehicle and a driver, and disconnect the high voltage battery from other components.
Accordingly, when a fault occurs in the components or system of the vehicle, the battery switch must be turned off, regardless of quantity of electric current flowing through the battery switch.
However, when the battery switch is turned off while high electric current flows, surrounding inductance causes overvoltage to a contact point of the switch. In this case, when the battery switch employs a mechanical contact point, contact fusion can be formed. In addition, when the battery switch is a semiconductor device, the components are damaged by the overvoltage.
If the high voltage battery is not disconnected from the system due to the fusion or damage of the battery switch, secondary accident can occur and a driver can be electrically shocked.
To solve this problem, electric vehicles and hybrid vehicles employ a power relay assembly as a power shut-off device to supply and shut off power from the high voltage battery to the motor via a power control unit (PCU). The power relay assembly serves as a safety device for completely shutting off power in the event of system error, repair, or the like.
The power relay assembly includes a high voltage relay such as a pre-charging relay (450V, 5 A or higher), a main relay (450V, 60˜150 A or higher), and the like.
The high voltage relay has a mechanical relay structure in which special gas, for example, H2 gas, is injected and sealed to prevent a spark that is likely to occur at a contact point of the relay when it supplies or shuts off high voltage/high current.
Therefore, the high voltage relay is heavy due to the special gas and increases the gross weight of the power relay assembly, thereby decreasing fuel efficiency.
The background technique of the present invention is disclosed in Korean Patent Publication No. 2010-0062702A (Publication date: Jun. 10, 2010, entitled “Device for protecting battery switch and method thereof”).